Heretofore, rotor assemblies have included magnets selectively placed within various encompassing sleeve and/or housing arrangements, wherein the final assembly is retained together by rivets (U.S. Pat. Nos. 3,657,582 and 2,060,259), or by being heat shrunk together (U.S. Pat. No. 3,531,670), or by being punch rammed together (U.S. Pat. No. 4,433,473), or by a locking wedge action (U.S. Pat. No. 4,339,874). In the Commutator Assembling Machine shown and described in U.S. Pat. No. 2,755,538, a staking ram is used to stake the cylindrical upper end of a central sleeve against a concentric chamfered surrounding locking ring, within a plurality of radially positioned wedge-shaped commutator conducting bars.